Intraluminal prostheses used to maintain, open, or dilate blood vessels are commonly known as stents. Stent constructions generally include lattice type cylindrical frames that define a plurality of openings. Common frameworks for stents include individual rings linked along the length of the stent by a linking member, a continuous helically wrapped member (that may include one or more linking members), a braid or a mesh formed into a tubular structure, and a series of interconnected struts. Stents are either self-expanding or balloon expandable. Self-expanding stents are delivered to a blood vessel in a collapsed condition and expand in vivo following the removal of a constraining force and/or in the presence of an elevated temperature (due to material properties thereof), whereas balloon expandable stents are generally crimped onto a balloon catheter for delivery and require the outwardly directed force of a balloon for expansion. Stents can be made of various metals and polymers. Stents can also be made of bioabsorbable materials, such as described in U.S. Pat. No. 6,245,103 to Stinson et al., which is incorporated by reference in its entirety into this application.
Synthetic vascular grafts are routinely used to restore the blood flow in patients suffering from vascular diseases. For example, prosthetic grafts made from expanded polytetrafluoroethylene (ePTFE) are commonly used and have shown favorable patency rates, meaning that depending on a given time period, the graft maintains an open lumen for the flow of blood therethrough. Grafts formed of ePTFE include a microstructure characterized by spaced apart nodes connected by fibrils, the distance between the nodes defined as internodal distance (IND).
It is known in the art to use stents in combination with vascular grafts to form stent-grafts. In one type of stent-graft, individual rings without a linking member are spaced apart along a length of the stent-graft. The rings may be encapsulated between two layers, such as described in U.S. Pat. No. 5,123,917 to Lee, or may be disposed on a surface of a graft, such as described in U.S. Pat. No. 6,364,903 to Tseng et al., each of which is incorporated by reference in its entirety into this application.
The following references relate to stent-grafts: U.S. Pat. No. 6,626,939, U.S. Pat. No. 6,733,524, U.S. Pat. No. 7,108,716 and U.S. Pat. No. 7,285,132, each of which is incorporated by reference in its entirety into this application.
Applicants have recognized that it would be desirable to provide a stent-graft including an ePTFE graft and discrete bio-resorbable members, embodiments of which are described herein along with methods of making same.